The present invention is related to a cell culture dish.
Cell culture dishes are dishes with a lid, which are used in the biological or medical laboratory for cell culture and in order to cultivate micro-organisms (microbes and fungi) and higher cells (for instance, mammalian cells, cell tissue etc.). In a round, transparent realisation they are also designated as Petri dishes.
U.S. Pat. No. 3,055,808, the entire contents of which is incorporated herein by reference, discloses a Petri dish for the cultivation of micro-organisms in particular, comprising a flat cylindrical dish and a lid. The dish has an upper lateral edge, extending circumferentially and sealing the lid. The cup-shaped lid has the same shape, but a greater diameter, so that it fits slackly to the dish. At one corner between a covering wall and a circumferential side wall, the lid has a pressure sensitive, permanently tacky adhesive for detachably fastening the lid on the dish and for hermetically sealing the connection between lid and dish. The adhesive extends in the circumferential direction along the upper edge of the dish and along the inner surfaces of the perimeter of the covering wall at the corner. The lid is made of a flexible material, which is realised such that it bends when a lateral pressure is applied to its side wall, and consequently the seal between the lid and the dish is released, the adhesive remaining on the lid when the lid is removed from the dish.
The Petri dish serves for the culture of micro-organisms, of bacteria in particular. The Petri dish is hermetically closed when the lid is put on. The lid has no aeration position. An increased contamination through microbial growth might occur when the adhesive is applied, so that the expense for sterilisation is increased. The tacky property of the adhesive may be altered by a long storage time, increased temperature in the incubator, influence of low temperatures or contact with culture medium. Through this, the sealing between the lid and the dish may be compromised. Also, ingredients of the adhesive may contaminate the culture medium.
The company BD Biosciences, San Jose, USA offers Petri dishes having a diameter of 50 mm and a height of 9 mm under the designation “BD Falcon” and with the article number 35106. The Petri dishes are made of polystyrene and have a lid that has a sealing seat on the dish. For this purpose, the dish has a conical sealing seat on the upper edge of a circumferential side wall, and the lid has a complementary sealing seat on the inner wall of a lid side wall. The lid is adapted to be clampingly seated onto the sealing seat of the dish, i.e. there is a frictional connection as soon as the lid is put up. In this, the length of the side wall of the lid does not exceed the conical region of the side wall of the dish. The complementary sealing seat is a result of this, but no lever action can deform the lid when it is opened. The Petri dish has no defined aeration position with an aeration gap between lid and dish. Once the lid is sealingly put on, this Petri dish cannot be opened in a simple way, but an increased expenditure of force has to be applied for this task instead. It is not possible to handle this Petri dish by one hand only, in particular not when opening it. In order to overcome the frictional connection, the user must take the Petri dish at the lower dish with one hand and hold it fast, and with the other hand he must strongly pull upward the lid of the Petri dish. In such a handling it is unavoidable that turbulences arise in the culture medium in the Petri dish, by which sensible cells, manipulated cells in particular (for instance transformed and/or infected cells etc.), can be influenced negatively, for instance they detach from the bottom of the dish, and thus become useless. In addition, these turbulences are accompanied by formation of droplets/aerosols like a drizzle, so that a drizzle/aerosol of culture medium is burst into the air of the surroundings and contaminates the same when the Petri dish is opened. This is dangerous and thus undesired in the cultivation of pathogenic organisms in cells (viruses, mycoplasma, prions etc.) or of cells which excrete a toxin into the culture medium, because the user is exposed to a health hazard by this.
For incubating or cultivating, respectively, cells or micro-organisms respectively are introduced into a cell culture dish. In a common procedure, the dish is covered up by putting up a slackly sitting lid in order to protect the cells or micro-organisms, respectively. The cell culture dish is set into an incubator in which optimum conditions for the incubation or cultivation respectively are generated by adjusting an atmosphere and temperature that is suited for this. The atmosphere in the cultivator is normally formed by air having a certain content of CO2 and O2 in a certain air humidity. The slackly laying lid permits the atmosphere present in the incubator to be present also within the cell culture dish, i.e. on the cells or micro-organisms, respectively. Moreover, cell culture dishes are known wherein the lid has a greater distance from the dish by punctual knobs, so that the gas exchange with the interior of the cell culture dish is more markedly.
From U.S. Pat. No. 5,520,302, the entire contents of which is incorporated herein by reference, a rectangular Petri dish for cultivating micro-organisms is known. It has a rectangular dish with a bottom wall and a circumferential side wall, which projects upward from the bottom wall. Further, the cell culture dish has a rectangular lid, which is adapted to be mounted in two different positions. The lid has a covering wall and a circumferential exterior as well as a circumferential interior lid side wall, both extending downward from the covering wall and limiting an endless groove. The contour of the endless groove corresponds to the upper end of the side wall of the dish. When the lid completely covers up the dish in a first position, the upper end of the side wall is prevented from engaging completely into the groove, so that no passage of gas between lid and dish would be possible. However, in case that the lid is positioned completely above the dish in a second position, being turned about 180°, the upper end of the side wall engages completely into the groove. Passage of gas between lid and dish is prevented through this.
In the known Petri dish, the lid has to be put onto the dish in the correct alignment in order to permit the passage of gas between lid and dish. For gas-tight closure of the Petri dish, the lid has to be taken off and put up anew after rotating it about 180°. Handling the Petri dish is made more difficult through this. Moreover, the micro-organisms may be contaminated in these manipulations. Further, the atmosphere in the interior of the Petri dish can adapt itself to the composition of the surroundings when the lid is reset, so that the culture conditions in the interior of the Petri dish are not preserved any more.
U.S. Pat. No. 4,675,298, the entire contents of which is incorporated herein by reference, discloses a Petri dish with a circular lower dish and a lid that is slackly disposed thereon. Projections are disposed on the perimeter of the inner side of the lid, and indentations matching the same are formed on the edge of the dish. This permits to adjust a gap between the lid and the dish in order to control the gas exchange between the interior of the Petri dish and the atmosphere. In order to adjust the gap, the lid must be rotated with respect to the dish, which necessitates using both hands. For this purpose, the user has to take the Petri dish out of an incubator at first, as the case might be. Because the lid sits slackly on the dish, the Petri dish is not liquid-tight, even when the gap between dish and lid is closed completely. Due to this, spillage of culture medium or micro-organisms, respectively, might occur in the manipulation of the Petri dish.
Starting from this, the present invention is based on the objective to provide a more user-friendly Petri dish. With user-friendly is to be understood in particular: simple manual and/or automatic handling (repeatable opening, repeatable closing and/or carrying the cell culture dish) with only one hand or an automatic tool, respectively. Moreover, the term “user friendly” is intended to mean also low-risk with respect to potential contamination of the user, i.e. the risk of the user to be exposed to contaminated (infected or toxic) culture medium is minimised.